title: Overexpression of cell surface cytokeratin 8 in multidrug-resistant MCF-7/MX cells enhances cell adhesion to the extracellular matrix.
abstract: Accumulating evidence suggests that multiple complex mechanisms may be involved, simultaneously or complementarily, in the emergence and development of multidrug resistance (MDR) in various cancers. Cell adhesion-mediated MDR is one such mechanism. In the present study, we initially observed increased cell adhesion to extracellular matrix proteins by the MDR human breast tumor cell line MCF-7/MX compared to its parental cells. We then used a strategy that combined antibody-based screening technique and mass spectrometry-based proteomics to identify membrane proteins that contribute to the enhanced adhesion of MCF-7/MX cells. Using MCF-7/MX cells as immunogen, we isolated a mouse monoclonal antibody, 9C6, that preferentially reacts with MCF-7/MX cells over the parental MCF-7 cells. The molecular target of 9C6 was identified as cytokeratin 8 (CK8), which was found to be overexpressed on the cell surface of MCF-7/MX cells. We further observed that down-regulation of cell surface levels of CK8 through siRNA transfection significantly inhibited MCF-7/MX cell adhesion to fibronectin and vitronectin. In addition, anti-CK8 siRNA partially reversed the MDR phenotype of MCF-7/MX cells. Taken together, our results suggest that alterations in the expression level and cellular localization of CK8 may play a significant role in enhancing the cellular adhesion of MDR MCF-7/MX cells.
authors.affiliation: State Key Laboratory of Experimental Hematology, Institute of Hematology & Hospital of Blood Diseases, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, PR China.
authors.forename: Fang
authors.initials: F
authors.lastname: Liu
authors.forename: Zhong
authors.initials: Z
authors.lastname: Chen
authors.forename: Jinhong
authors.initials: J
authors.lastname: Wang
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Shao
authors.forename: Ziyou
authors.initials: Z
authors.lastname: Cui
authors.forename: Chunzheng
authors.initials: C
authors.lastname: Yang
authors.forename: Zhenping
authors.initials: Z
authors.lastname: Zhu
authors.forename: Dongsheng
authors.initials: D
authors.lastname: Xiong
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism*; D015536:Down-Regulation; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D005109:Extracellular Matrix / Q000473:pathology / Q000502:physiology*; D005260:Female; D005353:Fibronectins; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D053533:Keratin-8 / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008942:Mitoxantrone; D016133:Polymerase Chain Reaction; D040901:Proteomics; D034741:RNA, Small Interfering; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D018709:Statistics, Nonparametric; D053719:Tandem Mass Spectrometry; D019096:Vitronectin
chemical_list: D000911:Antibodies, Monoclonal; D005353:Fibronectins; D053533:Keratin-8; D034741:RNA, Small Interfering; D019096:Vitronectin; D008942:Mitoxantrone